Bae Seongman, Lim Joon Seo, Kim Ji Yeun, Jung Jiwon, Kim Sung-Han
Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Clinical Research Center, Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Immune Netw. 2021 Feb 22;21(1):e9. doi: 10.4110/in.2021.21.e9. eCollection 2021 Feb.
The most important characteristics of coronavirus disease 2019 (COVID-19) transmission that makes it difficult to control are 1) asymptomatic and presymptomatic transmission, 2) low incidence or lack of dominant systemic symptoms such as fever, 3) airborne transmission that may need a high infectious dose, and 4) super-spread events (SSEs). Patients with COVID-19 have high viral loads at symptom onset or even a few days prior to symptom onset, and most patients with COVID-19 have only mild respiratory symptoms or merely pauci-/null-symptoms. These characteristics of the virus enable it to easily spread to the community because most patients are unaware of their potential infectivity, and symptom-based control measures cannot prevent this type of transmission. Furthermore, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is also capable of airborne transmission in conditions such as aerosol-generating procedures, under-ventilated indoor spaces, and over-crowded areas. In this context, universal mask-wearing is important to prevent both outward and inward transmission until an adequate degree of herd immunity is achieved through vaccination. Lastly, the SSEs of SARS-CoV-2 transmission emphasize the importance of reducing contacts by limiting social gatherings. The above-mentioned transmission characteristics of SARS-CoV-2 have culminated in the failure of long-lasting quarantine measures, and indicate that only highly effective vaccines can keep the communities safe from this deadly, multifaceted virus.
2019冠状病毒病（COVID-19）传播难以控制的最重要特征包括：1）无症状和症状前传播；2）发病率低或缺乏如发热等主要全身症状；3）空气传播，可能需要高感染剂量；4）超级传播事件（SSEs）。COVID-19患者在症状出现时甚至症状出现前几天病毒载量就很高，且大多数COVID-19患者只有轻微呼吸道症状或仅有轻微/无明显症状。病毒的这些特征使其能够轻易传播至社区，因为大多数患者并未意识到自身潜在传染性，基于症状的控制措施无法预防此类传播。此外，严重急性呼吸综合征冠状病毒2（SARS-CoV-2）在诸如产生气溶胶的操作、通风不良的室内空间和人员密集区域等条件下也能够进行空气传播。在此背景下，在通过接种疫苗实现足够程度的群体免疫之前，普遍佩戴口罩对于防止病毒向外和向内传播都很重要。最后，SARS-CoV-2传播的超级传播事件凸显了通过限制社交聚会来减少接触的重要性。上述SARS-CoV-2的传播特征导致长期检疫措施失效，并表明只有高效疫苗才能保护社区免受这种致命的、多方面的病毒侵害。
